As is well known, turbines have a shaft with a rotor mounting a number of rotor blades. When a fluid, such as a gas, passes across the rotor blades, the rotor and connected shaft rotates and produces useful work such as driving a compressor or the like.
One example of a turbine is a gas turbine wherein combustion gases from one or more combustion chambers flow past the rotor blades to rotate the shaft which, in turn, drives an axial air compressor. The compressed air from the air compressor is supplied to the combustion chamber for mixing with fuel for combustion. Another example of a turbine is a turbo-compressor. In rocket engines, compressed gases such as oxygen and hydrogen are mixed in a combustion chamber, reacting explosively to create high temperature gases which are exhausted through the rocket nozzle to produce thrust. A portion of the exhaust gases is directed to one or more turbo-compressors. As with the gas turbines described above, the turbo-compressors have a rotating shaft mounting a rotor with a number of rotor blades. The exhaust gases are directed to the blades to rotate the rotor and shaft to drive a compressor to compress the hydrogen or oxygen for delivery to the combustion chamber.
To guide the combustion gases to the blades, turbines, and more particularly turbo-compressors, include an annular, stationary stator nozzle. The stator nozzle typically has a number of vanes spaced and shaped to distribute and direct the flowing gases in the desired manner to the rotor blades. As can be appreciated, the stator nozzle must be capable of withstanding the high temperatures of the combustion gases. Furthermore, at start-up when the turbocompressor is cold, the nozzle must be capable of either withstanding or means must be provided for minimizing thermal stresses produced when the hot gases encounter the relatively cold stator nozzle vanes. Along these same lines, it is often practiced that the rocket engine nozzle and turbo-compressor are quenched with cryogenic gas when the rocket engine is shut down. The cryogenic gas may be at temperatures at or about -380.degree. F. (80.degree. R.). Again, the stator nozzle must be capable of withstanding or means must be provided for minimizing the thermal stresses when the -380.degree. F. (80.degree. R.) gas encounters the hot, for example, 2040.degree. F. (2500.degree. R.), stator nozzle.
It has been known to provide exotic materials and production methods to produce stator nozzles capable of withstanding the temperatures and thermal-stresses set forth above. This, however, has resulted in expensive stator nozzles which still are subject to failure due to the extreme environment in which they operate.
In addition to the thermal stresses attributed to temperature differentials, the vanes are also subjected to external forces. One source of such external forces are those reaction forces resulting from the flowing gases encountering and being turned by the vanes which are held by suitable supports. The vanes must be able to withstand these forces. Another source of forces being loaded upon is attributable to the vane supports. Typically, the vanes are secured to the supports at either end against both axial and tangential movement. Due to misalignment of these supports, occurring during assembly, or during operation because of thermal expansion or creep or the extreme operating pressures bending or compressive loads may be imposed on the vanes. Furthermore, misalignment of the vanes may cause the reaction forces to unevenly load the stator vanes. The potential for bending and/or compression loading, and an uneven loading of reaction forces has caused certain materials, such as ceramics which are relatively inexpensive but brittle, to be overlooked as materials for manufacturing the stator nozzle vanes. There is, therefore, a need for a means to support the stator nozzle vanes to assure that the vanes will not be subject to bending or compressive forces and that regardless of misalignment, the reaction forces will be equally distributed at the ends of the vanes.